[Eeglablist] A second ICA after removing components?

[Baris Demiral]

Yes, but this is not providing any benefit for us then. There are cheaper
ways (manual or automatic) to reject such bad epochs any ways.

I wonder whether when we reject the bad ICs, it should/could/does back
project to the ERP and corrects the corrupt activity as we expect.
For instance, compare FASTER or ADJUST algorithms, can't you do similar
things via EEGLAB functions? I suppose  you can. When you use ADJUST, the
ERP activity is cleaned from the noise mapped by the ICs.

Baris

On Mon, Aug 15, 2011 at 5:09 PM, Maximilien Chaumon <
maximilien.chaumon at gmail.com> wrote:

> Hello all,
>
> I'm currently cleaning data before working with components.
>
>    - I cut my dataset into epochs
>    - reject epochs where signal is bad
>    - run an ICA
>    - find blink and muscle components, reject them
>    - run an ICA again, and look at my components.
>
> ... as I understood was suggested at the bottom of this page
> http://sccn.ucsd.edu/wiki/Chapter_01:_Rejecting_Artifacts
>
> Then the ICs look very nice but come in pairs of extremely similar
> topographies with different time courses, as shown on this picture<http://oszilla.hgs.hu-berlin.de/public/2ICAs.png>
> .
> I am wondering what happened here. I can imagine that rejecting components
> before running the second ICA is what went wrong... But why did I read that
> on the wiki?
>
> Thanks a lot for any advice.
> Max
>
>
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-- 
SB Demiral, PhD.
Department of Psychology
7 George Square
The University of Edinburgh
Edinburgh, EH8 9JZ
UK
Phone: +44 (0131) 6503063
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